arindam77 wrote:moving bed and sponge filters are the best filters, but we are habituated to think costlier is more efficient. How many of us take full advantage of smart phones, but we all have at least 1 in our pocket, some doesn't fit in pockets too.Don't know about handling 100 gallons, but they are very efficient. I once tried to build one moving bed sand filter, but it had design flaws, as the cheap power heads don't provide a constant pressure.

Does the sand really have to move that fast as they show in YT. I mean, as long as it shuffling, shouldn't it allright?

Congrats, for the first build.I think it's the sump. So, how thick is the glass ? Seems too thick.Pondguru's moving bed filter doesn't move that much, it's like shivering. Though the media is different.https://www.youtube.com/watch?v=BwNhEvouMDw

arindam77 wrote:Congrats, for the first build.I think it's the sump. So, how thick is the glass ? Seems too thick.Pondguru's moving bed filter doesn't move that much, it's like shivering. Though the media is different.https://www.youtube.com/watch?v=BwNhEvouMDw

Thanks, Yeah you guessed right, its the sump. I've used 8 mm saint gobain extra clear glass for the sump. I am sure that i could have gotten away with 6 mm, but just playing safe here, keeping some room for beating.There is no way i could justify why i got the extra clear glass for the sump, when its going to be tucked away under the table all the time.Guess was just being whimsical.

As for the media. I guess if i could get the water moving through the sand bit evenly and as long as the particles are bumping into each other, they should be ableto scrape the old bacteria film off each other. I mean it doesn't really have to be at supersonic speed, do they?Your thoughts.

Moving bed filters don't restrict water flow, and does nothing for mechanical filtration. So, the sand has to be suspended, and in my experience, moving the sand slowly is very difficult. It's like, not moving> more flow>not moving >more flow>started jumping>reduce flow>not moving (again). It's like Pass-Fail, nothing in between.

This is how the seams turned out to be, not sure if it can be seen clearly in the picture. However, there is a gap between the glasses of approx 1mm filled with silicon and has hardened now. But will wait for another 48 hrs before i fill it up to do leak test. Also need to fill the gaps left by the spacers.

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Seems you made a mistake, silicone is not to be injected while the spacers are in position.You should have made like point soldering with silicone while the spacers are in position, around 1 foot apart, then let the points cure, then remove spacer, trim the excess silicone at the points soldered/ joined both inside and outside and then inject silicone along the whole seam.And you should put the tape at narrower margin, so that less silicone is visible.Now, i see why there was mess with silicone.Anyway, it's the sump. Better luck next time. I will try to draw a image showing steps, if time permits.